SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '350342a2ece12b5bee350c632909ae8d64dda9b2fda167a06e3f639a37511a45' 
  AND token = 'U6t54LgfE0UwiiiJq5KlX4LCNuW+ouMg7mlKCR1gTgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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