SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ab5948460491bc4b1963bbab5d1619e4ee857218ae53d154d8447d03e7e5399' 
  AND token = 'K/yBP6fw+a7anAwntF8vRBnYybUwJuz5sgd1Vl+75ck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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