SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51de99131e7eab323fd29ff89f5b8adc248f80e1b58073e8e7bd2cca0bc340d8' 
  AND token = 'K34BjaND5T+J7/9h+CuKegPT4RiEDVYr7ZVPyvpEMMo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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