SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96bc5ab60fc42ce2d49868cf1543c674e008e3a475f9852ae3e71c2901fb51cd' 
  AND token = '66ngdQs/tTZthZw3gv/muLz+w/BHT1tT+EBF1uVo8nI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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