SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab29393cfb5dca9884557894f5523066e89256648eb1978795f5f8ced9e5f1c7' 
  AND token = '8I2b50nqVPaclLtxl/alMJ/X/ZBOKuMJ+M+EVwGlslo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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