SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '161b282efb2526739254659f30ab9d07eb28d504e33c0318a6583b00fd8edec7' 
  AND token = 'RztvlLST6QSWboWHqxXm64NZ5YNuV2SGj7PQxDsmza0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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