SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '940d40592a15e37e92cc10afd82e27797f58f126b1eb7a0aaf13d08619038f74' 
  AND token = 'njov31fe7QpNia1ljuVuDxMgA9QHnWtBB5jQXRIR6GM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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