SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '586270819b1f0016c0a17e73b9bfcf200defa9d187482d96b4565d490a4d7b35' 
  AND token = 'pukK8iu+bSH6JI3RY+P6YgoTncxsoG1LCUfj7n/qKCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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