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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '334c7a4f9c5302d844809b6509d509f8d43965aa1cd53e1bf88df53230dc6fa9' 
  AND token = '7vSBzcIXztZ43bntJASXwL9QAAI3oA3IMdeUVgXKPz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}