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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff9bc03374ffb9d84aaf684427c579e0a95f9b50ddb0fba0d9ced86c74f0833a' 
  AND token = 'qBjbPK0Z1s/dZ2e2fZPsgIh0cjoT0pqtmzEGNdlDtOM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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