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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2821014d7fbd12bc0404ffed898d4089e9c0a621e07ef58157ba3a0509fe13c9' 
  AND token = '+SP4MvW1FfYmfOYDlNPeO9M0EQvk1VslCpew8rdhUaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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