SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f7e24c6b3f611983903b687e3cfd538b5a8d968cf02ecc7421af2cc99d3a746' 
  AND token = 'kg0RFq/Y8t6mo+X8g5iq7BSaR+jO5cv+Fv1FdACKlSw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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