SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd1ca7e6646b9187ef056f47cd3ec13e0414757ad998e4d9b5727a759480da6bc' 
  AND token = 'RUq5sRBXXWKFvtJa4OjfB+ZgMHRvo2Zq9gLEy7YaTWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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