SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b0c3bc1f01897aa03691be8763346d8e75c6fb23f619f0da5d2ce51e3a031aa' 
  AND token = 'GaUAkThEbESSMRqhpL8pP7OtdSYfbO/mmC7VGvyq2Ck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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