SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f730f163cffc80c14c5fd17a96101aad2a19e76ee060f07b0819566bf7d6df9' 
  AND token = 'isUTRkP8cv9/Tv1PhPFBJzPHzq1PUJHm04QUmS9+PIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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