SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0fcb51e37472cecde579ccb9a6cca3dc70324054bfbb92eeb736fe443cf1e55b' 
  AND token = 'alE2kVb+zWH36eSZB22MNLYxSn9gkuegCSyyQf1KWg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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