SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21bde954a1f062e3bda2191cd6e69cf4f6bbdfdf42226f94732e4c9aebfec195' 
  AND token = 'ITUXbQlKjvVgmSORWIstKJBCDp2hproo5hlz9oror2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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