SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c60824999b50f76f49b001c9b793af87914a0543e93e6d1940cd0328ba237d0a' 
  AND token = 'PE1iMXKynVc+EqOwQJgBj2VxZJppfOY3bRG1QxuiKVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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