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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c1ec8c7d9f9844e85447a8620ce300362ab3a5f8f8c5dac05588125d3eb6ea4' 
  AND token = 'LeLUCqysCiAbeBzhfMr4nobNi2g2JIjfz+GDxk/oMLk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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