SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b5621f6a3ac4be27582a01007019a7cd8de35c39a0fe8c70900688619dc67b7' 
  AND token = 'C1oTAe3SLqpAZ5rYz+PDtFOEO61E1pIaTU5C0bPvVzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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