SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48c0b32bbc4956ad218ebea914250f1f34e537671e5e9964def95c431a71dca9' 
  AND token = 'ohJdnJotaEYoJ6Yar9BPT7IRE5Ss0WpRxuvOm7BUejc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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