SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8578991be2061af37a971b2a094952dbe87f1c7327e7b92fb413507bdf34711' 
  AND token = 'gNnSeigBHkspiCRmlaOGz6dVCL1hY3E5Ed8woPS/nKc=' 
  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"
    }
  }
}