SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c5b15feaca5814aa97ffbf2bf02703d668c4a743b423bdaf60f3a37bb12cbbd0' 
  AND token = 'CUEvsFWlY/da7uVcaJ4tF9fZ9OknouMrStsbFvPHvg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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