SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acc8c5885b23826eaeb64d8fd1feb0c85b6ac9ea50b9e63fdc56870494b2373a' 
  AND token = 'tRErpERIddQKprE0zrjxRdV0z5nlGQnjTVT5tYdzMjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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