SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '520871fdef854a613506940d6c6da3c13f7f408e62353576b91608429abc095b' 
  AND token = 'Mw4k4IHDK4Zp5Jzwhnc1GihVs1n44KHACfVlQ3/SSqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}