SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '683df5b0b5904151c979f5cbd4e3d477065eabb0e2f49f71ee19c2d43a9298eb' 
  AND token = 'UaYKxRyPaMVbxSPJUq5SAYeWEvR1u/Q+k5hFLm9j3u4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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