SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f9fc1ef8018555c5ffd1c18594d97a5f97dfee80599fa98353d9917c40c57bd' 
  AND token = 'Z1sznrgFnM3Z4TDNUVD8g3dxUWqteYfe2m3jEp1tjqE=' 
  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"
    }
  }
}