SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '349670eedf3c099220535f80b518edac29caacd2e7252d71785a3f7f2a1325cb' 
  AND token = 'PLJb3dZanHN4Jh2JXvWBe9K4aiRZmdItWJ8lYKaAtyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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