SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a14e52d7fc1f36dfd70ad5c32b0a844a47a9c31115a309dfdc74f6246d5cc911' 
  AND token = 'mSXhKP2q/CliYSJeywRuwfrcEHZVvEtDTRUM7duAzrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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