SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ff93411718d85ea3eb255963712072c1283766d141646eeead45e1c07dd6a6f' 
  AND token = 'ij73xV+c38kTg+++yO0z7yp7tXxcwHg6jrX98q923UI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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