SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '208286e1188486d54d9395f5c427dfbac8ac11b10e08c225782a3ae508a14616' 
  AND token = 'PkPkrFEtVQXNxE33I5IXrGAtgbqdF8KhIIoEZeqS8HA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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