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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a50721c08e7b63127acff4bee3b45ffafb1a4ffc3b9a4e55ccfb9376e9beae4' 
  AND token = 'QIU1ogyWpx0mBkAoWGWdcXGcL5vow7FHNQV0OLDhGEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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