SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8a6b3378ddbc564a035f14e60a5ea13b730f36c196e21a0b1d9faa98ace85fc' 
  AND token = 'rzd+L3PHVebha8pCQfHSczaqi52qFoMjryVO6xnIM/0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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