SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8e908ca70b88ff191a0aa6d0cc576a08ec727c4d35810206710288ad54e4a6c' 
  AND token = 'wf9WS3sW1Qa0tKxVTKf7ZnWHvyA3KiuEBXxBXK0IJbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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