SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68311102c78d0f87bcf78bc217c2dcdd8d388600ca00a1b285f274b56f9138ca' 
  AND token = 'AyQ0XoRREj7Oy1Zx/O7AREXww+D7mu3tfH42oaKIIBs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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