SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '300c04393dd684684fbd8ad7a0da39860f968098a1c3f95564ddc55fb83eda20' 
  AND token = '8q+iCEekwbPE+//1T+/tu5cWZzikyMIysKnJ2cYe4Bk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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