SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6df99972f67a0de4c021ce65d112da07a8084efcf054f6b7cd04bafac93f4618' 
  AND token = '0T91vj4/a9qSRguijirLCwB0wYQZmd6DIgFVPAIvMK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}