SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5e190268b442770f0e3506752667155f7b9de097ec3c18f002c26f586a26e00' 
  AND token = 'Q+VBV8qPaAgK+RgAtXkpeZj4XIv9Z945VBm9abvzxUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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