SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd50037c40ee23346ca8ddb1a5be5dd90ad50cbca28aa144e0e7956a383a9ac17' 
  AND token = 'YPGBJrGeDUASMw+WoxVCuQLuksTDO2blgAzvOd8Xcag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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