SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7637f51e4a8f649a64949335b3c6cb4cb72ee5d3408a1812d828b42dd99da49' 
  AND token = 'AjE4pQBVAnnwXJPq2gJ0PWqmOWBGMmhRxz88eU1FaAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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