SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '173377680453cad837428198bb41f5650ec15c8afffe906547bc6baadd1236b6' 
  AND token = '39iU+fq3JUVf9os1IzTD+YLkAmV/70MzM7FQhv2fwWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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