SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3b4d9a4ed0b32f65034751526b12a57095e3b70e1fac4946488df32880f6443' 
  AND token = 'spJdjwH9BnWkBAsqrEYVoUHAmgLpA3PcCospJMGMUO0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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