SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c033a877bb96f56c40b61e014440ab785bca9c7031090d6de9effe851493355a' 
  AND token = 'RW+tBtELCRq1Bj9mg8mlpnqohvrq/ATbY/qkCzwKSx4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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