SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5e0218fe7fad00ea89cc2d68c2dfa15e2c4ac4ab102e397193e4ea383287790' 
  AND token = 'lXGVvxUTws86JyKG2whYnmHaywKckeYkREFEskvW4PA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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