SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43a2131895e774b662c7a1eb48a9fc0596bef1457eb1505fd7d6b766b17ca6c2' 
  AND token = 'RIbFnYQJXLakTdiLBqo9dk/qZRAEQQnJoryDFPk3L/c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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