SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15b5500ca09d96ba5ecbbd9d5deb35aba4f0bce8165640e2b68950e3a7cae820' 
  AND token = '4iUFjJRXuxIrKsiv01PF+8VSrvqZdHnXrndFuIavPsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00050

JSON explain

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