SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3505bb33b6ccbc0ca6cd018be535ca7c2fd038713125a8433108deb2d977d1c' 
  AND token = 'xRTSfLXA4k4RYEeTBhJKCBDAOeika3rAGrBYk/tTxH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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