SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7bf9ccc663794c221fc0fe57f2370b144901536a355048f6409d644249b640a' 
  AND token = 'QZqu29E88y8IwWZrVGPwV97I20aXBBcIp/PcyuAX4CY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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