SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '500d13618f602743f679deb396356ae98df4d7d2df9d336d18b0198329608d39' 
  AND token = '57WGsfqSMwrWQlEigDfYjppX2cWYCURhpiL8KCOwl9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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