SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f31743a9f97d5502797c776d842e0dd52269e189268c13488de8fd1b8a260a7c' 
  AND token = '9854I/DG5xTdzjKpU44o+eiBl6ynWCPFC/5KdujvmfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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