SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f71ac0896e4e5cc91e4c52c89e1d693306d88bb7d6d2f6719ccf8ef10318f84' 
  AND token = '+Z5VFzmy/HgUUK7xEqN57fTiZ71QWL4FUzYjOI+yDnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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