SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc51ea7aa243401262aec7773d050314d23ae4435788440d5ad7f6ab95452cf0' 
  AND token = 'rt31jRtCBjGbClkTlIpUHXXhjlWZoMyAf1YKqvkqEwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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