SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe9105cdf7f62a05475a266e5d01d312cfcc72778301a8affeb56fc317f2aca6' 
  AND token = 'UQcTVESQtMIVag/zfM5v0y/uQsfli6oE+4u368RvAFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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