SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ffd3b1ee25571241d21412c127f7466c3778ca4e0c91bfaf9df99519d9af8c0' 
  AND token = 'Z0T3YjSLejSg+mBqBGibVIWd7YLcFklGE4RDAZn4Sgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00063

JSON explain

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