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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd976dca8f3d019f3e103c0afa3d5d5fc9f00df067fd750ad80f6c1b36cef0250' 
  AND token = 'r9+DiLBnrNYLIZ6AicrlXms6inVvd+Estz7TkDhDLKQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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