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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fb0c4e6bd5e41990d5246f7568a21bdc99e48b6b6d3016c5b6e27203b36f9dd' 
  AND token = 'tL7FSFqkLnfuH5zDIHtXXDElf/OL5uHTQYBPVvLnDsw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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