SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c407ce53fdb42eed7704f711068c753d99b65390cc52070dfea70680567bbe7' 
  AND token = 'grOfXVDtpnzhxIAIuE16HNtAN41W62cOm47zZDfcWKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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