SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6abd97167840324f7d3ea02879e8940fe619254c917da29a78025945a8ab452a' 
  AND token = 'h78lMjPrtygCUgh8UhWyQP4HaJlJfiB00vK6WHVXMG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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