SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d17ca43659ea3d6a6ffa37e84ccce05902e70a5671a1404babff51a1a9314e3' 
  AND token = 'VgaxY2bdXAFqbLu4+3u5tvuXI6xcEhkbEN7qUFvqfxQ=' 
  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"
    }
  }
}