SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad2fe70bbc5c2c8a9010be934500afab5db9264455d8bf1eeddcc9cc79a898be' 
  AND token = 'tSSGm7mXxTmhZA2XnVG4KdLLDGQ/xLetsfbWd8DVNaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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