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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2bd5639d0edce2710b57c2be2b8b2f741c255a7e4421bf67905bc7237cc0d4e' 
  AND token = 'GZ9OIXpEzj+GOTKmiJNfvE/9bJE4Qo5RyeLMOjtuRYY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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