SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8f0e20fce9088d960609ca519405548fe42490603a6fa6c3dd06706920be634' 
  AND token = 'BiqpFIUAqhGz+Rdh1s+17znnsmrY4kxBq416aQTSB5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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