SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a16c8c371d347d25b4847810da356aa36212c11e4b92cbed74e93d33c3c352cc' 
  AND token = '9g5GyCimRXC0wROcPOMYbZFAwEpdrfThlHE8kGbu/TY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}