SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0b314aaae760a8cff9d5ef2300cee799b8625bfb65f4fbf8ea3a0fdc4831a79' 
  AND token = 'YV8b1pu8bt8EKiaaIKYrjDDI94xBwQoY6YtFdZlIUxE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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