SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aea7738945daf8680c6488973b58fe76621f8cd148ff13e762aac7e7b4943499' 
  AND token = 'j+o6x9+SANTCHrxaMFTWF2P/EzdMgTvghm415HmZzUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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