SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56c61a2399e146c3d0fec84af3b0fe498888b621ddd76e47ef640538f9c63d79' 
  AND token = 'lkvZ6vxL3xxY8Vu3y2mJ2iwbJ2LSAPodR1EsLtljLqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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