SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a771d61df97f4c13072c3c469e0b97705ac48983346c1cba2faf1ccee35d0e8a' 
  AND token = 'RPLXtPjrK0TJVErWnGhybH2f8LWyuYA9rmB2HMY+rvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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