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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc4b352c62a8c237edfba07035352a9cdb31bb198e9ba0e42ff36ecdf4e55a2a' 
  AND token = 'fXSxRI0MbZSlJrvdZCITL4DG6/Qtvq+p8Hd15PpFyIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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