SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8696f5b472fef9f4c3970c4f9cc6c88ac3743a1b2fe921af1e4b28defe0f8d6' 
  AND token = 'c9gqPVChvGd/fqFpjUzhuyzL1pOd5BnQUQQvWPw5V4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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