SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '755442f408769cf2640c5ef51de2c3ccc171be71c3190305848bcb3fab8d2ca5' 
  AND token = '1FjB9OEUtR6Rk//TjfnChIwnAEVsrgO+Oa9BrjqaylI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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