SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57f658a2bc50ef098c5081cd7503a0bc8f050d242ecb02c4185f10c2d0604a2c' 
  AND token = 'FWkXROgK6vmhT5xmb0GTIjqOAkdgieiLE/bSUp9NU2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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