SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15d420f98a6cd7ed613102d81cb784f2e2fc952e11ea09aa5b5226bd99e3a963' 
  AND token = 'z4JcZfHE5fJm5BY0/6eLypcPW+qH6jbLdiUbsukzDW8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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