SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '435f6c4bdbbf97fd9ca7152000dfea12b0d2e9c471e28a922cff2b0a992eadce' 
  AND token = 'kQit9BdWQY/ifkSzVTBrZE0G70aB37c1EiINMrg7IUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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