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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '756ae87e9e84f6d6fc0c3fa2488c9ac2ccb189fe705fb205e2a2cb18eeb70d79' 
  AND token = 'QV1duNsob05IYRuiL8eV4RzHv8vLOtFiLXSjtbc01Sg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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