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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2ed7a02923bd5abdca57c818baf798b999ccb7b5f11ef33e5dcf07084f21ebe' 
  AND token = 'sb4qO/VaxauXpa0/7XNeoAjVg5Ry+fnDVWDI/uqhxoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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