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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8b8c461ac4acbdaf5a02ce874771c224aa49c2148883747a52d7e3b0ba31cd6' 
  AND token = 'wnnj5ZlaOR0ErzoSGTgafbvhDOPVVpCtSgdZB7dPcSQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}