SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ee9c5a2d4a87c816c89921c7a0f15542b4a809e2c148574f84fefe6571fc446' 
  AND token = '3/BfW5yoK7vd9KQ5ZVi8T9ilpoqFQBB3YJX/ZfuD1Yw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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